White blood cells such as lymphocytes, monocytes, basophils, eosinophils and neutrophils are present in normal peripheral blood. Abnormal white blood cells which are not present in normal peripheral blood appear in diseases such as viral infections or hematopoietic tumors. Abnormal white blood cells include, for example, reactive lymphocytes which have been activated by antigen stimulation.
For example, Japanese laid-open patent No. 2012-233754 discloses a method of classifying and counting white blood cells which is capable of discriminating blasts and atypical lymphocytes in addition to classifying and counting normal white blood cells.
Atypical lymphocytes include reactive B lymphocytes and reactive T lymphocytes. However, although the method disclosed in Patent Document 1 can discriminate atypical lymphocytes, this method cannot discriminate and count reactive B lymphocytes alone. A blood analyzer and blood analyzing method capable of discriminating and counting reactive B lymphocytes is therefore desirable.